1. Field of the Invention
The present invention pertains to an information reproducing apparatus for reproducing digital information composed of coded signals of audio and video.
2. Description of Related Art
Various coding (data compressing) technologies have been proposed to compress data size of audio or video at high efficiency. For example, in the field of portable music players, the music player conforming to the MPEG Audio Layer 3 (MP3) system (xe2x80x9cMPEGxe2x80x9d is short for xe2x80x9cMoving Picture Experts Groupxe2x80x9d), the coding system for recording a larger quantity of music signals at a higher sound quality in a semiconductor memory of a limited capacity is becoming pervasive. Besides the MP3 system, new coding systems are provided one after another such as the Advanced Audio Coding (AAC) system and the Windows Media Audio (WMA) system.
Generally, in the field of severe competition of new product development, the life cycle of products is very short. For example, when a new system is widely spread, the reproducing apparatus conforming only to the former coding system may not be applicable to the new system, and the user has to purchase a new product conforming to the new system.
In such reproducing apparatus, however, the hardware configuration is not so much different if the coding system is changed, and only the algorithm differs slightly in the portion for decoding the information.
Accordingly, a reproducing apparatus applicable to different coding systems by realizing the decoding process by decoding software and installing plural types of decoding software on a semiconductor memory mounted on the reproducing apparatus has been developed. In addition, a reproducing apparatus applicable to the new decoding technology by rewriting a coding program installed in a semiconductor memory mounted on the reproducing apparatus is also developed.
A portable music player applicable to plural types of coding systems is disclosed, for example, in Japanese Patent Laid-Open Publication (Kokai) No. H11-167400. FIG. 1 is a functional block diagram showing a schematic configuration of a compact music player 100 disclosed in this publication.
As shown in FIG. 1, the compact music player 100 has an input I/F unit 102, a first semiconductor memory 103, a second semiconductor memory 104, a digital signal processing circuit 105, and a Digital to Analog (D/A) converter 106. In the input interface (I/F) unit 102, audio digital data coded by using a predetermined audio coding technology is inputted. In the first semiconductor memory 103, audio digital data inputted from the input I/F unit 102 is stored. In the second semiconductor memory 104, a decoding program inputted from the input I/F unit 102 to decode in reverse process of coding is stored. The digital signal processing circuit 105 decodes the audio digital data stored in the first semiconductor memory 103 by the decoding program stored in the second semiconductor memory 104. The D/A converter 106 converts the output signal from the digital signal processing circuit 105 into an analog signal.
According to the compact music player 100, using the decoding program, stored in the second semiconductor memory 104, corresponding to the audio digital data stored in the first semiconductor memory 103, the audio digital data stored in the first semiconductor memory 103 is decoded. Therefore, music can be reproduced from the audio digital data regardless of the compression coding system of audio digital data stored in the first semiconductor memory 103.
In the compact music player 100, whole or part of the second semiconductor memory 104 is composed of a programmable flash memory. Accordingly, if the corresponding decoding program is not written preliminarily in the second semiconductor memory 104, a new decoding program can be stored by updating the content of the second semiconductor memory 104, so that music signals corresponding to various compression decoding systems can be reproduced.
In addition, in the compact music player 100, plural types of decoding processing programs are installed on the second semiconductor memory 104. Based on the information about the coding process added to each music digital signal, a decoding process program corresponding to the compression coding system can be selected from the plural types of decoding process programs, and decoding is processed, so that music signals corresponding to various compression coding systems can be reproduced.
In such reproducing apparatus, however, to be applicable to plural types of coding systems, a sufficient capacity must be kept in the semiconductor memory to install plural types of decoding program. However, the programmable and nonvolatile semiconductor memories such as flash memories are expensive, and if a flash memory of a large capacity is incorporated, it adds to the cost of the reproducing apparatus.
Although the semiconductor memory storing the decoding programs stores plural types of decoding programs by increasing its capacity, only one of decoding programs corresponding to the coding system of the music digital data is used while actually reproducing the music digital data. Therefore, it is not an efficient manner in the use of the expensive semiconductor memory.
Moreover, in order to suppress the capacity of semiconductor memory, it may be considered to store a corresponding decoding program every time to update the content of the semiconductor memory to be applicable to the plural types of decoding systems. In this method, however, in order to install a corresponding decoding program, an external device such as a personal computer is required to connect to the reproducing apparatus each time. In other words, in a place where the personal computer or other external device is not available, the corresponding decoding program cannot be installed on the reproducing apparatus. The portable music player is often used outdoors, its convenience is restricted significantly.
An apparatus for reproducing digital information coded in a coding system in an embodiment of the present invention, the coded digital information and a decoding program describing a decoding algorithm to decode the digital information recorded in an information recording medium, includes: a reading unit configured to read out the coded digital information and the decoding program recorded in the information recording medium; a program memory configured to store the decoding program read out from the reading unit; a signal processing unit configured to decode the digital information read out from the reading unit by the decoding algorithm of the decoding program stored in the program memory; and a conversion unit configured to convert the digital information decoded in the digital signal processing unit into a predetermined format, and to output the converted digital information.
An information recording medium in an embodiment of the present invention, recording digital information to be reproduced by an information reproducing apparatus configured to decode the digital information and to convert the decoded digital information into a predetermined output format, includes: a digital information file storing the digital information coded the digital information in a predetermined coding system; and a program file storing a decoding program describing a decoding algorithm to decode the coded digital information.
A method for reproducing digital information in an embodiment of the present invention includes: reading out coding information of the digital information to be reproduced from an information recording medium in which the digital information coded in a predetermined coding system and a decoding program describing a decoding algorithm to decode the coded digital signal are recorded together; reading out the decoding program corresponding to the coding information read out from the information recording medium; storing the read out decoding program to a program memory; reading out the digital information to reproduce from the information recording medium; decoding the digital information read out by the decoding algorithm of the stored decoding program; and converting the decoded digital information into a predetermined format, and reproducing the converted digital information.
An apparatus for recording digital information coded in a coding system and decoding program describing a decoding algorithm to decode the digital information in a first recording medium in an embodiment of the present invention, the decoding program and recording software to record the digital information in the first recording medium recorded in a second recording medium, includes: a first input/output unit configured to input and output of the first recording medium; a second input/output unit configured to input and output of the second recording medium; a program memory configured to store the recording software in the second recording medium through the second input/output unit; and a control unit configured to read out coding information from the digital information, to judge whether the decoding program corresponding to the coding information readout is recorded in the first recording medium through the first input/output unit, to read out the decoding program corresponding to the coding information from the second recording medium through the second input/output unit when the decoding program is not recorded in the first recording medium, to record the decoding program read out in the first recording medium through the first input/output unit, and to record the digital information in the first recording medium through the first input/output unit, according to a processing procedure predetermined in the recording software stored in the program memory.
A method of recording digital information coded in a predetermined coding system in a first recording medium, in an embodiment of the present invention, includes: reading out coding information from the digital information; judging whether decoding program corresponding to the coding information read out is recorded in the first recording medium; reading out the decoding program corresponding to the coding information from a second recording medium when the decoding program is not recorded in the first recording medium; recording the decoding program read out in the first recording medium; and recording the digital information in the first recording medium.
A computer readable recording medium storing a program for recording digital information coded in a predetermined coding system in a first recording medium, in a embodiment of the present invention, includes: reading out coding information from the digital information; judging whether decoding program corresponding to the coding information read out is recorded in the first recording medium; reading out the decoding program corresponding to the coding information from the second recording medium when the decoding program is not recorded in the first recording medium; recording the decoding program read out in the first recording medium; and recording the digital information in the first recording medium.